Histograms in heavy-quark QCD at finite temperature and density

TL;DR

This paper investigates the phase transitions in heavy-quark lattice QCD at finite temperature and density using histogram methods, identifying critical points and the effects of the sign problem.

Contribution

It introduces a histogram-based approach to locate critical points and analyze the phase structure in heavy-quark QCD at finite density, including the effects of the complex phase factor.

Findings

Identified the critical point where the transition changes from first-order to crossover.

Estimated the small impact of the sign problem near the critical point.

Mapped the critical surface in 2+1 flavor QCD across all chemical potentials.

Abstract

We study the phase structure of lattice QCD with heavy quarks at finite temperature and density by a histogram method. We determine the location of the critical point at which the first-order deconfining transition in the heavy-quark limit turns into a crossover at intermediate quark masses through a change of the shape of the histogram under variation of coupling parameters. We estimate the effect of the complex phase factor which causes the sign problem at finite density, and show that, in heavy-quark QCD, the effect is small around the critical point. We determine the critical surface in 2+1 flavor QCD in the heavy-quark region at all values of the chemical potential mu including mu=infty.